As an example of a complex substance, one can cite: a) graphite; b) hydrogen; c) table salt; d) sulfur

Graphite is a simple substance. One of the modifications of carbon. Has a layered structure, metallic luster, and also has excellent thermal conductivity. It is widely used in industry.
Hydrogen is also a simple substance. It is designated by the symbol H. It is widely distributed in nature. Has several isotopes (deuterium, tritium). It is a constituent part of a huge number of chemical compounds (for example, water).
Sulfur is a simple substance.
Table salt is a complex substance. Consists of a molecule of sodium and chlorine. Has the formula NaCl.

One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.